Newsgroups: comp.robotics
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From: browen@lyapunov.aoc.nrao.edu (Bruce Rowen)
Subject: Re: laser diode safety
In-Reply-To: nagle@netcom.com's message of Fri, 27 Aug 1993 06: 52:14 GMT
Message-ID: <BROWEN.93Aug27092853@lyapunov.aoc.nrao.edu>
Sender: news@nrao.edu
Organization: National Radio Astronomy Observatory, Socorro NM
References: <1993Aug26.084151.2444@hemlock.cray.com>
	<1993Aug26.151805.28818@newshub.ariel.yorku.ca>
	<nagleCCEoF2.KzD@netcom.com>
Date: Fri, 27 Aug 1993 15:28:52 GMT
Lines: 36



	  Where did you get these things?  I've never seen a laser diode
   that could handle 10 AMPS.  Around 30mA is typical for a 5mW laser diode.
   Laser diodes are available up to about 30mW (interestingly, they don't
   draw much more current than the 5mW diodes; they're more efficient, with
   better mirrors.)  And they cost from $20 to around $150.
   I'd love to get a few of these giant 10A laser diodes for anything like $5.

					   John Nagle

The key to getting a large amount of power through a diode is to play
with the thermal duty cycle limits. The 30mA you quote is most likely
a *continious* current. If I ran 10A through my diode for more than a
few milliseconds, the thing would explode!. This is true for most IR
transmitters, you can safely up the current while reducing the duty
cycle of on/off times. 

My diode is basically a standard IR transmitter with a largeish heat
sinking surface behind the substrate. The data sheet calls it a laser
diode, but it is nothing like the diodes in semiconductor lasers that
have all the extra goodies to focus the beam and not burn up. The
sheet also says the max current of this device is 15amps, but after
blowing up some smaller devices, I though i'd back off on this on a
little.

I found the thing in one of those "newspaper like" electronic surplus
catalogs for $4.95. The thing is physically simmilar to a TO-5
transistor case.
--
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Bruce Rowen 				National Radio Astronomy Observatory
Scientific Programmer				Array Operations Center
browen@aoc.nrao.edu			  P.O. Box O  Socorro, NM   87801
(505)385-7329					     (505)385-7000
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